The present invention generally relates to apparatus for automatically advancing a length of plastic fastener tape used in reclosable packaging by a predetermined distance.
During the automated manufacture of reclosable bags, successive sections of a continuous length of thermoplastic fastener tape unwound from a supply reel or spool are joined (e.g., by conductive heat sealing) to successive sections of a continuous web of bag making material (e.g., a monolayer of thermoplastic film or a laminate comprising a layer of thermoplastic film). The web-to-fastener tape sealing operation can be performed either intermittently or continuously. Often the fastener tape has sliders inserted thereon, one slider per section, before that section is joined to the bag making material. In the latter event, it is also customary to form one slider end stop structure per section of the fastener tape prior to the latter being joined to the bag making material.
When the fastener tape carries a repeating structural feature (e.g., a slider or slider end stop structure), it is important that that those structural features be accurately placed at regular intervals to ensure that the structural features and the respective pockets or receptacles of the packages or bags are in proper registration. In particular, each slider end stop structure must be correctly aligned with a respective cross seal formed on the package or bag.
There is a continuing need for improvements in automated equipment for ensuring correct registration of slider-carrying fastener tape with precursor packages or bags on a packaging or bag making machine.